The Department of State Health Services said Sunday that the recalled 5- and 25-pound bags of Uncle Ben’s rice are primarily purchased by institutional settings such as schools and prisons. Some warehouse club retailers also stock the bags.

Health officials issued the recall Friday after students and staff in Katy who ate the rice at lunch became ill. Their symptoms included burning, itching, rashes, headaches and nausea. The symptoms passed within two hours.

Health officials say the cause of the illness remains undetermined.

Mars Foodservices US says it voluntarily recalled the products “out of an abundance of caution.”